Cell penetrating peptides for intracellular delivery of molecules

ABSTRACT

A cell-penetrating peptide characterized in that it comprises an amino acid sequence: X 1 X 2 X 3 WWX 4 X 5 WAX 6 X 3 X 7 X 8 X 9 X 10 X 11 X 12 WX 13 R (SEQ ID No: 10), wherein X 1 , is beta-A or S, X 2  is L or none, X 3  is R or none, X 4  is L, R or G, X 5  is R, W or S, X 6  is S, P or T, X 7  is W or P, X8 is F, A or R, X 9  is S, L, P or R, X 10  is R or S, X 11  n is W or none, X 12  is A, R or none and X 13  is W or F, and wherein if X 3  is none, then X 3 , X 11  and X 12  are none as well.

This application is the National Stage filing of PCT/EP2013/070680,entitled “CELL PENETRATING PEPTIDES FOR INTRACELLULAR DELIVERY OFMOLECULES” with the International Filing Date of Oct. 4, 2013, whichclaims the benefit of priority from PCT/IB2012/055344, filed on Oct. 4,2012.

The content of the following submission on ASCII text file isincorporated herein by reference in its entirety: a computer readableform (CRF) of the Sequence Listing (file name: VMAahF644s356_ST25subsl.txt, date recorded: Jun. 23, 2016, size: 27 KB).

The present invention pertains to the field of intracellular delivery ofmolecules such as nucleic acids and small hydrophobic molecules. Inparticular, the invention relates to a new cell-penetrating peptide(CPP) family, which exhibits high efficacy, low toxicity and isparticularly efficient for transdermal applications.

Although small molecules remain the major drugs used in clinic, innumerous cases, their therapeutic impact has reached limitations such asinsufficient capability to reach targets, lack of specificity,requirement for high doses leading to toxicity and major side effects.Over the past ten years, in order to circumvent limitations of smallmolecules and of gene-based therapies, we have witnessed a dramaticacceleration in the discovery of larger therapeutic molecules such asproteins, peptides and nucleic acids which present a high specificityfor their target but do not follow Lipinski's rules. Pharmaceuticalpotency of these molecules remains restricted by their poor stability invivo and by their low uptake in cells. Therefore, “delivery” has becomea central piece of the therapeutic puzzle and new milestones have beenestablished to validate delivery strategies: (a) lack of toxicity, (b)efficiency at low doses in vivo, (c) easy to handle for therapeuticapplications (d) rapid endosomal release and (e) ability to reach thetarget. Although viral delivery strategies had given much hope for geneand cellular therapies. their clinical application has suffered fromside- and toxicity-effects [1,2]. Researches were mainly focused on thedevelopment of non-viral strategies, and different methods have beenproposed including lipid, polycationic nanoparticles and peptide-basedformulations, but only few of these technologies have been efficient invivo and have reached the clinic. Cell Penetrating Peptides (CPP) areone of the most promising non-viral strategies. Although definition ofCPPs is constantly evolving, they are generally described as shortpeptides of less than 30 amino acids either derived from proteins orfrom chimeric sequences. They are usually amphipathic and possess a netpositive charge [3-5]. CPPs are able to penetrate biological membranes,to trigger the movement of various biomolecules across cell membranesinto the cytoplasm and to improve their intracellular routing, therebyfacilitating interactions with the target. CPPs can be subdivided intotwo main classes, the first requiring chemical linkage with the cargoand the second involving the formation of stable, non-covalentcomplexes. CPPs from both strategies have been reported to favour thedelivery of a large panel of cargos (plasmid DNA, oligonucleotide,siRNA, PNA, protein, peptide, liposome, nanoparticle . . . ) into a widevariety of cell types and in vivo models [3-7].

Twenty years ago, the concept of protein transduction domain (PTD) wasproposed based on the observation that some proteins, mainlytranscription factors, could shuttle within cells and from one cell toanother [for review see ref 3,4]. The first observation was made in1988, by Frankel and Pabo. They showed that thetranscription-transactivating (Tat) protein of HIV-1 could enter cellsand translocate into the nucleus. In 1991, the group of Prochiantzreached the same conclusions with the Drosophila Antennapediahomeodoinain and demonstrated that this domain was internalized byneuronal cells. These works were at the origin of the discovery in 1994of the first Protein Transduction Domain: a 16 mer-peptide derived fromthe third helix of the homeodomain of Antennapedia named Penetratin. In1997, the group of Lebleu identified the minimal sequence of Tatrequired for cellular uptake and the first proofs-of-concept of theapplication of PTD in vivo, were reported by the group of Dowdy, for thedelivery of small peptides and large proteins. Historically, the notionof Cell Penetrating Peptide (CPP) was introduced by the group of Langel,in 1998, with the design of the first chimeric peptide carrier, theTransportan, which derived from the N-terminal fragment of theneuropeptide galanin, linked to mastoparan, a wasp venom peptide.Transportan has been originally reported to improve the delivery of PNAsboth in cultured cells and in vivo. In 1997, the group of Heitz andDivita proposed a new strategy involving CPP in the formation of stablebut non-covalent complexes with their cargo [7]. The strategy was firstbased on the short peptide carrier (MPG) consisting of two domains: ahydrophilic (polar) domain and a hydrophobic (apolar) domain, MPG wasdesigned for the delivery of nucleic acids [7]. The primary amphipathicpeptide Pep-1 was then proposed for non-covalent delivery of proteinsand peptides [8]. Then the groups of Wender and of Futaki demonstratedthat polyarginine sequences (Arg8) are sufficient to drive small andlarge molecules into cells and in vivo. Ever since, many CPPs derivedfrom natural or unnatural sequences have been identified and the list isconstantly increasing. Peptides have been derived from VP22 protein ofHerpes Simplex Virus, from calcitonin, from antimicrobial or toxinpeptides, from proteins involved in cell cycle regulation, as well asfrom polyproline-rich peptides [reviews 4-6].

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows secondary structure prediction for various VEPEP-9peptides. H: helix; T: turn.

FIGS. 2A, 2B, 2C, and 2D show the binding of VEPEP-9a (2A), VEPEP-9b(2B), VEPEP-9d (2C), and VEPEP-9f (2D) peptides with various cargoes, asmonitored by fluorescence spectroscopy using either intrinsic Trp ofVEPEP-9 or extrinsic fluorescently labeled cargoes.

FIG. 3 shows the particle size distribution of several VEPEP-9/cargocomplexes (VEPEP-9a/siRNA, VEPEP-9b/peptide, VEPEP-9c/PNA,VEPEP-9f/Doxo, and VEPEP-9c/AZT) at cargo/VEPEP-9 molar ratio of 1/20(as determined by dynamic light scattering).

FIG. 4 shows the dose-response of VEPEP-9-mediated delivery of C4peptides on proliferation in Hela, MCF7, HEK, HS-68, and U2OS cells.VEPEP-9a or VEPEP-9f peptides were used for C4 delivery.

FIG. 5 shows the dose-response of VEPEP-9-mediated delivery of siRNAtargeting Cyclin B1 on proliferation in Hela, MCF7, HEK, HS-68, and U2OScells. VEPEP-9b or VEPEP-9e peptides were used for siRNA delivery.

FIG. 6 shows the dose-response of VEPEP-9-mediated delivery of C4peptides on G2 arrest in Hela, MCF7, HEK, HS-68, and U2OS cells.VEPEP-9a or VEPEP-9f peptides were used for C4 delivery.

FIG. 7 shows the dose-response of VEPEP-9-mediated delivery of siRNAtargeting Cyclin B1 on G2 arrest in Hela, MCF7, HEK, HS-68, and U2OScells. VEPEP-9b or VEPEP-9e peptides were used for siRNA delivery.

FIG. 8 shows the toxicity profile of VEPEP-9 particles on U2OS andSTEM-ES cells (as determined by MTT assay and by cyclophilin mRNAlevel). VEPEP-9a, VEPEP-9b, VEPEP-9c, VEPEP-9d, VEPEP-9e, and VEPEP-9fpeptides were complexed with either peptide or siRNA.

FIG. 9 shows the dose-response of VEPEP-9-mediated delivery of a CyclinB1 antisense peptide nucleic acid (PNA) on Cyclin B1 protein levels incells. VEPEP-9a and VEPEP-9f peptides were used for PNA delivery.

FIG. 10 shows the dose-response of VEPEP-9-mediated delivery ofdoxorubicin (Doxo), porphyrin (POR), or taxol (TX) on cancer cellproliferation. VEPEP-9a, VEPEP-9b, VEPEP-9d, and VEPEP-9f peptides wereused for delivery in MCF-7 and SCK-3-HEK2 cells.

FIGS. 11A and 11B show schematics for the formation of NANOPEP particleshaving multilayer organization.

FIGS. 12A and 12B show reduction of tumor growth by intratumoral (IT) orintravenous (IV) administration of NANOPEP particles containing C4peptide in PC3 (12A) or SKB-HEK3 (12B) xenograft mice. NANO-9A/C4:VEPEP-9a/C4 core, coated with VEPEP-9a; NANO-9F/C4: VEPEP-9f/C4 core,coated with VEPEP-9f; NANO-9A-PEG/C4: VEPEP-9a/C4 core, coated withPEG-VEPEP-9a; C4S: VEPEP-9 NANOPEP particles with scrambled C4 peptide.

FIGS. 13A and 13B show reduction of tumor growth by intratumoral (IT) orintravenous (IV) administration of NANOPEP particles containing siRNAtargeting Cyclin B1 in PC3 (13A) or SCK3-HEK2 (13B) xenograft mice.NANO-9b/siRNA: VEPEP-9b/siRNA core, coated with VEPEP-9b; NANO-9e/siRNA:VEPEP-9e/siRNA core, coated with VEPEP-9e; NANO-9A-PEG/C4: VEPEP-9a/C4core, coated with PEG-VEPEP-9a; siRNA: control siRNA targeting CyclinB3.

FIG. 14 shows reduction of tumor growth by intravenous administration ofNANOPEP particles containing antisense PNA targeting Cyclin B1 inSKB3-HEK2 xenograft mice. NANO-9A/PNA 5: VEPEP-9a/PNA core (5 μg PNA),coated with VEPEP-9a; NANO-9A/PNA 10: VEPEP-9a/PNA core (10 μg PNA),coated with VEPEP-9a; NANO-9A-PEG/PNA: VEPEP-9a/PNA core, coated withPEG-VEPEP-9a; NANO-9c/PNA 5: VEPEP-9c/PNA core (5 μg PNA), coated withVEPEP-9c; NANO-9c/PNA 10: VEPEP-9c/PNA core (10 μg PNA), coated withVEPEP-9c; NANO-9c/a-PEG/PNA: VEPEP-9c/PNA core, coated withPEG-VEPEP-9a.

FIG. 15 shows survival of SKB3-HEK2 xenograft mice followingadministration of NANOPEP particles containing doxorubicin (DOXO).NANO-9a/DOXO: VEPEP-9a/DOXO core, coated with VEPEP-9a; NANO-9F/DOXO:VEPEP-9f/DOXO core, coated with VEPEP-9f; NANO-9a-PEG/DOXO:VEPEP-9a/DOXO core, coated with PEG-EPEP-9a; DOXO: DOXO alone.

FIG. 16 shows in vivo biodistribution of fluorescently labeled peptide(PEP) or siRNA delivered by intravenous, intrarectal, intranasal ortransdermal administration of VEPEP-9 NANOPEP particles (as determinedby live fluorescence animal imaging). NANO-9a/PEP: VEPEP-9a/peptidecore, coated with VEPEP-9a; NANO-9b/siRNA: VEPEP-9b/siRNA core, coatedwith VEPEP-9b.

DETAILED DESCRIPTION

The inventors have now designed a new family of cell-penetratingpeptides for the delivery of peptides/proteins, hydrophobic and chargedmolecules, named VEPEP-9. Delivery strategies using VEPEP-9 peptides asthe outer layer of nanoparticles are referred to as NANOPEP-9.

VEPEP-9 are short secondary amphipathic peptides forming stablenanoparticles with molecules such as small peptides, peptide analogues,small oligonucleotides or derived and small hydrophobic or chargedmolecules, hereafter designated as “SHM”. VEPEP-9 vectors comprise thefollowing amino acid sequence: X₁X₂X₃WWX₄X₅WAX₆X₃X₇X₈X₉X₁₀X₁₁X₁₂WX₁₃R(SEQ ID No: 10), wherein:

X₁ is beta-A or S;

X₂ is L or none;

X₃ is R or none;

X₄ is L, R or G;

X₅ is R, W or S;

X₆ is S, P or T;

X₇ is W or P;

X₈ is F, A or R;

X₉ is S, L, P or R;

X₁₀ is R or S;

X₁₁ is W or none;

X₁₂ is A, R or none; and

X₁₃ is W or F; and

wherein if X₃ is none, then X₂, X₁₁ and X₁₂ are none as well.

According to a particular embodiment of the VEPEP-9 cell-penetratingpeptides according to the invention, the vector comprises an amino acidsequence of 19 or 20 amino acids, which consists of:X₁X₂RWWLRWAX₃RWX₄X₅X₆WX₇WX₈R (SEQ ID No: 11), wherein:

X₁ is beta-A or S;

X₂ is L or none;

X₃ is S or P;

X₄ is F or A;

X₅ is S, L or P;

X₆ is R or S;

X₇ is A or R; and

X₈ is W or F.

According to preferred embodiments of VEPEP-9 vectors as described inthe above paragraph, illustrated in the experimental part below, theamino acid sequence of the cell-penetrating peptide is selected from thegroup consisting of

VEPEP9a1:  (SEQ ID No: 1) X₁LRWWLRWASRWFSRWAWWR VEPEP9a2: (SEQ ID No: 2) X₁LRWWLRWASRWASRWAWFR VEPEP9b1:  (SEQ ID No: 3)X₁RWWLRWASRWALSWRWWR, VEPEP9b2:  (SEQ ID No: 4) X₁RWWLRWASRWFLSWRWWR,VEPEP9c1:  (SEQ ID No: 5) X₁RWWLRWAPRWFPSWRWWR, and VEPEP9c2: (SEQ ID No: 6) X₁RWWLRWASRWAPSWRWWR,

wherein X₁ is beta-A or S.

According to another embodiment of the VEPEP-9 cell-penetrating peptidesaccording to the invention, the vector comprises an amino acid sequenceof 15 amino acids, which consists of: X₁WWX₂X₃WAX₄X₅X₆RX (SEQ ID No:12), wherein:

X₁ is beta-A or S;

X₂ is R or G;

X₃ is W or S;

X₄ is S, T or P;

X₅ is W or P;

X₆ is A or R; and

X₇ is S or R.

According to preferred embodiments of VEPEP-9 vectors as described inthe above paragraph, illustrated in the experimental part below, theamino acid sequence of the cell-penetrating peptide is selected from thegroup consisting of:

VEPEP9d:  (SEQ ID No: 7) X₁WWRWWASWARSWWR VEPEP9e:  (SEQ ID No: 8)X₁WWGSWATPRRRWWR and VEPEP9f:  (SEQ ID No 9) X₁WWRWWAPWARSWWR,

wherein X₁ is beta-A or S.

According to a particular embodiment of the present invention, theVEPEP-9 cell penetrating peptide is stapled, which means that itcomprises a chemical linkage (in addition to the amino acid chain)between two residues. In a particular embodiment of stapled VEPEP-9peptides, the VEPEP-9 peptide comprises a hydrocarbon linkage betweentwo residues which are separated by three or six residues. The skilledartisan can obtain these peptides by using techniques which areavailable in the art, for example as described by Verdine and Hilinski,Methods in Enzymology, 2012 [12].

VEPEP-9 strategy improves both ex-vivo and in vivo delivery andefficiency of peptide and analogue and small hydrophobic molecules,without activating the innate immune response or inducing toxic sideeffects.

According to a preferred embodiment, a cell-penetrating peptide of thepresent invention further comprises, covalently linked to the N-terminalend of the amino acid sequence, one or several chemical entitiesselected from the group consisting of an acetyl, a fatty acid, acholesterol, a poly-ethylene glycol, a nuclear localization signal, anuclear export signal, an antibody, a polysaccharide and a targetingmolecule (peptide, fatty acid, saccharide).

As developed below and shown at least in example 5 below, PEGylation ofVEPEP-9 peptides is particularly advantageous for stabilizingnanoparticles in vivo.

In addition or alternatively, a cell-penetrating peptide according tothe invention can comprise, covalently linked to the C-terminal end ofits amino acid sequence, one or several groups selected from the groupconsisting of a cysteamide, a cysteine, a thiol, an amide, anitrilotriacetic acid optionally substituted, a carboxyl, a linear orramified C1-C6 alkyl optionally substituted, a primary or secondaryamine, an osidic derivative, a lipid, a phospholipid, a fatty acid, acholesterol, a poly-ethylene glycol, a nuclear localization signal,nuclear export signal, an antibody, a polysaccharide and a targetingmolecule.

Another aspect of the present invention is a complex comprising acell-penetrating peptide as described above and a cargo selected amongstnucleic acids, proteins, peptides and hydrophobic molecules. Examples ofpolypeptide cargoes are small peptides, cyclic peptides, peptide-basedbiomarkers and bio-drugs. Examples of nucleic acid cargoes are chargedor uncharged small oligonucleotides, such as, for example, small singlestranded RNA or DNA (size between 2 to 40 bases) and double stranded RNAor DNA (size up to 100 base pairs), in particular siRNA selected tosilence a target mRNA. The cell-penetrating peptides according to theinvention can also be used to deliver a mix of several different siRNA,with an improved inhibiting activity. microRNAs (miRNAs), selected fortheir ability to affect expression of genes and proteins that regulatecell proliferation and/or cell death, can also be complexed withVEPEP-9. In another preferred embodiment of the complex according to theinvention, the cargo is a small molecule (size lower that 1.5 kDa),preferably hydrophobic, either hydrophobic or charged. Preferred cargosin the complexes according to the present invention are anticancer andantiviral drugs. Non-limitative examples of small hydrophobic moleculeswhich can be used include amino acid, di or tri peptide (labelled ornot) daunomycin, Paclitaxel, doxorubicin, AZT, porphyrin,fluorescently-labelled-nucleosides or nucleotides (FAM-Guanosine,CY5_UTP, CY3-UTP), hydrophobic maghemite (contrast agents or magneticnanoparticles Fe₂O₃) and fluorescent dyes.

The size of the complexes described above is preferably between 50 and300 nm, more preferably between 50 and 200 nm (the size of the complexherein designates its mean diameter).

In the complexes according to the invention, the cargo/VEPEP-9 molarratio depends on the nature and size of the cargo, but is generallycomprised between 1/1 and 1/50. For small peptide or oligonucleotidecargoes, the cargo/VEPEP-9 molar ratio preferably ranges from 1/5 to1/20. For small molecule cargoes, the cargo/VEPEP-9 molar ratiopreferably ranges from 1/3 to 1/10.

According to an advantageous embodiment of the complexes as describedabove, the VEPEP-9 peptides comprise a polyethylene glycol group or anacetyl group covalently linked to their N-terminus, and/or a cysteamidegroup covalently linked to their C-terminus.

The above complexes can be advantageously used as “core shells” forobtaining bigger complexes, or nanoparticles, by an additional step ofcoating the cargo/VEPEP-9 complex with another layer of cell-penetratingpeptides, which can be different from the VEPEP-9 peptides describedabove. Examples of such nanoparticles are VEPEP-9/CADY (wherein CADY isa CPP as described in EP1795539 and in [11]), VEPEP-9/PEP-1 (whereinPep-1 is a CPP as described in [8]), VEPEP-9/MPG (wherein MPG is a CPPas described in U.S. Pat. No. 7,514,530 and in [7, 10]), as well asnanoparticles covered by a CPP belonging to another VEPEP family, forexample selected from the following list:

VEPEP-3a:  (SEQ ID No: 25) Ac-X₁KWFERWFREWPRKRR-cysteamide VEPEP-3b: (SEQ ID No: 26) Ac-X₁KWWERWWREWPRKRK-cysteamide VEPEP-3c: (SEQ ID No: 27) Ac-X₁RWWEKWWTRWPRKRK-cysteamide, VEPEP-3d: (SEQ ID No: 28) Ac-X₁RWYEKWYTEFPRRRR-cysteamide, VEPEP-3e: (SEQ ID No: 29) Ac-X₁RWWRLWWRSWFRLWRR-cysteamide VEPEP-3f: (SEQ ID No: 30) Ac-X₁LWWRRWWSRWWPRWRR-cysteamide VEPEP-3g: (SEQ ID No: 31) Ac-X₁LWWSRWWRSWFRLWFR-cysteamide, VEPEP-3h: (SEQ ID No: 32) Ac-X₁KFWSRFWRSWFRLWRR-cysteamide, VEPEP-6a: (SEQ ID No: 33) Ac-X₁LFRALWRLLRSLWRLLWK-cysteamide VEPEP-6b: (SEQ ID No: 34) Ac-X₁LWRALWRLWRSLWRLLWKA-cysteamide VEPEP-6c: (SEQ ID No: 35) Ac-X₁LWRALWRLLRSLWRLWRKA-cysteamide  VEPEP-6d: (SEQ ID No: 36) Ac-X₁LWRALWRLWRSLWRLWRKA-cysteamide  VEPEP-6e: (SEQ ID No: 37) Ac-X₁LWRALWRLLRALWRLLWKA-cysteamide  VEPEP-6f: (SEQ ID No: 38) Ac-X₁LWRALWRLLRNLWRLLWKA-cysteamide, VEPEP-3bstapl: (SEQ ID No: 39) Ne-X₁KR _(S)WWERWWR_(S) SWPRKRK-cysteamideVEPEP-3estapl:  (SEQ ID No 40) Ac-X₁RWWR _(S)LWWRSWS_(S)RLWRR-cysteamide ST-VEPEP-6a: (SEQ ID No: 41)Ac-X₁LFRALWR_(S)LLRS_(S)LWRLLWK-cysteamide ST-VEPEP-6aa: (SEQ ID No: 42) Ac-X₁LFLARWR_(S)LLRS_(S)LWRLLWK-cysteamideST-VEPEP-6ab:  (SEQ ID No: 43)Ac-X₁LFRALWS_(S)LLRS_(S)LWRLLWK-cysteamide ST-VEPEP-6ad: (SEQ ID No: 44) Ac-X₁LFLARWS_(S)LLRS_(S)LWRLLWK-cysteamide ST-VEPEP-6b:(SEQ ID No: 45) Ac-X₁LFRALWRLLR_(S)SLWS_(S)LLWK-cysteamideST-VEPEP-6ba:  (SEQ ID No: 46)Ac-X₁LFLARWRLLR_(S)SLWS_(S)LLWK-cysteamide ST-VEPEP-6bb: (SEQ ID No: 47) Ac-X₁LFRALWRLLS_(S)SLWS_(S)LLWK-cysteamideST-VEPEP-6bd:  (SEQ ID No: 48)Ac-X₁LFLARWRLLS_(S)SLWS_(S)LLWK-cysteamide ST-VEPEP-6c:  (SEQ ID No: 49)Ac-X₁LFAR_(S)LWRLLRS_(S)LWRLLWK-cysteamide,as well as variants thereof (regarding the amino acid sequence and/orthe N- and C-terminal chemical groups), wherein X₁ is beta-A or S andwherein the residues followed by an inferior “s” are linked by ahydrocarbon linkage. Preferred variants of the above sequences forforming nanoparticles according to the invention are PEGylated at theirN-terminal extremity instead of acetylated.

Another aspect of the present invention pertains to nanoparticles madeof a “core shell” comprising a cargo and a first carrier molecule,surrounded by VEPEP-9 peptides. These are herein referred to as“NANOPEP-9” particles. NANOPEP-9 technology constitutes a “custom-built”delivery system containing a common core particle, trapping therapeuticmolecules, with surface VEPEP-9 peptides which are preferablyfunctionalized for tumour or tissue targeting in vivo. From a structuralpoint of view, NANOPEP-9 particles are constituted by a “core” which iscoated by a layer of VEPEP-9 peptides. The “core” corresponds to acomplex comprising a cargo and a vector or carrier such as a firstcell-penetrating peptide, a liposome, a polycationic structure, a carbonnanoparticle, etc. In NANOPEP-9 particles, the layer of VEPEP-9 peptides(peripheral peptide) stabilizes the particle and can be functionalized.Functionalizing NANOPEP-9 particle surface with either cholesterol,lipid, PEG-molecules etc. improves particles stability in vivo, favourstheir administration by either systemic or topical routes and allowsrapid liberation of active cargoes within tumor cells or tissues.Functionalization of the surface of NANOPEP-9 particles with small FABfragments, peptides, antibodies and lipids has been shown to favour invivo tissue or tumour targeting. Also, functionalizing NANOPEP-9particle surface with polysaccharide such as PLGA, can be used asformulation for slow release of drug and cargo and allow a long termresponse in vivo. As shown in Example 5 below, the inventors haveobserved that N-terminal PEGylation of at least part of the VEPEP-9peptides surrounding the NANOPEP-9 particles increases thebiodistribution of cargoes in the tumour (10 to 20-fold increase),probably by stabilizing the NANOPEP-9 particles in the plasma.

NANOPEP-9 technology improves both cellular and in vivo delivery ofbiologically active cargoes and has been validated on a large set ofcell lines including adherent and suspension cell lines, hard totransfect cell lines. NANOPEP-9 particles strongly interact with cellmembranes and enter the cell independently of the endosomal pathway orrapidly escape from early endosomes. NANOPEP-9 technology presentsseveral advantages including rapid delivery with very high efficiency,stability in physiological buffers, protection of the cargo againstdegradation, lack of toxicity and of sensitivity to serum, ability offorming mix nanoparticles, can be functionalized and have beensuccessfully applied to the delivery of different types of cargoes intoa large variety of cell lines as well as in animal models, therebyconstituting powerful tools for basic research and therapeuticapplications. NANOPEP-9 technology can be applied both at therapeuticand diagnostic/theragnostic levels.

In a particular embodiment of NANOPEP-9 particles according to thepresent invention, the cargo is complexed to a first cell-penetratingpeptide, which can be for example, selected amongst CADY, MPG, PEP-1,PPTG1, poly Arginine motif, VEPEP-family peptides (VEPEP-3, VEPEP-6,VEPEP-9, stappled-VEPEP-6 or VEPEP-3) peptides described above (such asSEQ ID Nos: 1 to 10 and 25 to 49 and variants thereof), or any otherknown CPP. This cargo/CPP complex is then coated with a layer of VEPEP-9peptides. According to this embodiment, the skilled artisan willadvantageously choose the first CPP depending on the nature of thecargo, so that the complex of cargo and first CPP is stable. Hence, awide diversity of cargoes can be included in NANOPEP-9 particles.

In the nanoparticles as above-described, the core/VEPEP-9 molar ratiodepends on the nature and size of the core, but is generally comprisedbetween 1/1 and 1/50. For small peptide/CPP cores, the core/peripheralVEPEP-9 molar ratio preferably ranges from 1/5 to 1/30, depending on thenature of peptide cargo (hydrophobicity and charge).

In a preferred embodiment of the nanoparticles according to theinvention, the size of the nanoparticle is between 20 and 300 nm.

According to an advantageous embodiment of the NANOPEP-9 particlesaccording to the invention, at least part of the VEPEP-9 peptidesforming the peripheral layer of the nanoparticles comprise apoly-ethylene glycol or an acetyl group covalently linked to theirN-terminus, and/or a cysteamide group covalently linked to theirC-terminus.

According to another preferred embodiment, the core shell of theparticles is coated with a VEPEP-9 peptide functionalized with NTA (forexample, a VEPEP-9 peptide with nitrilotriacetic acid covalently linkedto its C-terminus). This allows the subsequent attachment to the surfaceof the particle, of any protein (or other molecule) harbouring ahistidine tag. This strategy offers the major advantage of having acommon two-layer particles “NANOPEPHIS-9” that can be associated to anyHis-tagged molecule.

In particular embodiments of the complexes and nanoparticles accordingto the invention, at least part of the VEPEP-9 cell-penetrating peptidesare bound to a targeting molecule. In the case of NANOPEP-9 particles,examples of targeting molecules include: antibodies, nanobodies and Fcor FAB fragments targeting HEK2, MUC1, EGF or XCCR4, as well as ligands,especially targeting receptors which are over-expressed at the surfaceof certain cell-types, horning peptides specific of selected organs.Non-limitative examples of such ligands and homing peptides are:RGD-peptide, homing targeting peptides (brain NT1 peptide. Ganglion GMIpeptide, as well as all other previously described and selected peptidefor tissues and cell line targeting), folic acid, polysaccharides,Matrix metalloprotease targeting peptide motif (MMP-9 or MMP3 for tumourselectivity).

According to a particular embodiment of the present invention, thecomplexes or nanoparticles are formulated so that they can be storedduring several months without losing their stability and functionalefficacy. As disclosed in example 5 below, the complexes andnanoparticles of the invention can advantageously be lyophilized in thepresence of a sugar. Non-limitative examples of sugars which can be usedto that aim are sucrose, glucose, manitol and a mix thereof, and theycan be used, for example, in a concentration ranging from 5% to 20%,preferably 5% to 10%, it being understood that a concentration of 5% isobtained by adding 5 grams per liter of solution before lyophilization.

Another aspect of the present invention is the use of a complex ornanoparticle as above-described, as a medicament and as a marker or animaging agent.

The present invention also pertains to a therapeutic, cosmetic ordiagnostic composition comprising a complex or a nanoparticle asdescribed above. For example, a composition comprising a complex ornanoparticle having a peptide targeting protein/protein interactions,involving essential protein CDK and Cyclin required for cell cycleprogression as a cargo, and a targeting molecule specific for tumourcells (for example: RGD-peptide, folic acid, MUC-1 or HEK2 antibodies ornanobodies), is part of the present invention. Depending on theapplication, this composition can be formulated for intravenous,intratumoral, topical, intrarectal, intranasal, transdermal, orintradermal administration, or for administration via a mouth spray, orfor administration as a subcutaneous implant for slow release of a drug.

The present invention also pertains to a method for delivering amolecule into a cell in vitro, comprising a step of putting said cellinto contact with a complex or nanoparticle as described above.

Several aspects of the present invention are further developed in thefollowing examples, illustrated by the figures (which are described inthe examples).

EXAMPLES Example 1 Materials and Methods

VEPEP-9 Peptides

All the peptides were synthesized by solid-phase peptide synthesis usingAEDI-expensin resin with (fluorenylmethoxy)-carbonyl (Fmoc) on a PioneerPeptide Synthesizer (Pioneer™, Applied Biosystems, Foster City, Calif.)starting from Fmoc-PAL-PEG-PS resin at a 0.2 mmol scale. The couplingreactions were performed with 0.5 M of HATU in the presence of 1 M ofDIEA. Protecting group removal and final cleavage from the resin werecarried out with TFA/Phenol/H₂O/Thioanisol/Ethanedithiol(82.5/5/5/5/2.5%) for 3 h 30 min. All the peptides presented acysteamide group at the C-terminus and were acetylated at theN-terminus. The peptide synthesis started by the C-terminus, using anAEDI-expensin resin starting with a cysteamide link, as described byMery et al, 1992. All the peptides contained a beta-Alanine or a serineat the N-terminus to favour any further functionalization without usingthe C-terminal cysteamide group.

Functionalization of VEPEP-9

Two approaches were used for peptide functionalization

(1) Peptide conjugations with peptide, antibody, PEGylation, NTA,cholesterol, stearylation, were performed at the primary amino group ofthe N-terminal residue, through a beta alanine or serine. It isadvantageous to maintain the C-terminal cysteamide free, since it isknown to be required to stabilize the particle through disulfide bounds(SH—SH). Functionalized peptides were further purified by ReversePhase-HPLC and analyzed by electro-spray ionization mass spectroscopy.

(2) Peptide conjugations were also performed via disulfide bound usingthe SH-group of the cysteamide moiety of the peptide.

VEPEP-9-Funct-1: (SEQ ID No: 13)X-LRWWLRWASRW(A-F)SRWAW(W-F)R-CH₂-CH₂-SH VEPEP-9-Funct-2:(SEQ ID No: 14) Ac-LRWWLRWASRW(A-F)SRWAW(W-F)R-CH₂-CH₂-S-S-XVEPEP-9-Funct-3: (SEQ ID No: 15) X-WWGSWATPRRRWWR-CH₂-CH₂-SHVEPEP-9-Funct-4: (SEQ ID No: 16) Ac-WWGSWATPRRRWWR-CH₂-CH₂-S-S-X

X: Cholesterol, PEGylation, stearyl, palmitoyl, small FC or FABfragments, nanobody, nitrilotriacetic acid (2×NTA), tissues targetingpeptides (brain, lung, lymph node, pancreas . . . ).

VEPEP-9 Structure

VEPEP-9 peptides, except VEPEP-9c and VEPEP-9e, are secondary amphipaticpeptides; they are highly versatile and show a strong structuralpolymorphism. VEPEP-9 are unfolded in solution as a free form and adoptan alpha helical conformation in the presence of lipid or artificialcellular membranes as well as in the presence of cargos such as peptide,SMH and small oligonucleotide (FIG. 1, wherein “H” stand for “helix” and“t” for “turn”). In contrast VEPEP-9c and VEPEP-9e adopt a coil/turnorganization due to the presence of the proline residue in the sequence.The N-terminus domain of VEPEP-9c adopt an alpha helical conformation inthe presence of lipid or artificial cellular membranes as well as in thepresence of cargos.

Peptides

Peptides targeting CDK/Cyclin (C4: KKQVRMAHLVET (SEQ ID No: 50)) linearor cyclic version were obtained for Polypeptide. Fluorescently labelled(CY5 and CY3) tri (GWSC-dye (SEQ ID No: 51)) and tetra (GWASC-dye (SEQID No: 52)) peptides were also obtained for Polypeptide.

Oligonucleotides &siRNA

siRNAs and 5′ Alexa⁷⁰⁰ or fluorescein (5′-FAM) fluorescently labelledsiRNA were synthesized by Eurogentec (Belgium) according to thefollowing sequences:

Cyc-B1 sense (SEQ ID No: 17) 5′GGCGAAGAUCAACAUGGCATT3′ Cyc-B1 antisense(SEQ ID No: 18) 5′UGCCAUGUUGAUCUUCGCCTT3′ Cyc-B3 sense (SEQ ID No 19)5′GGUGAAGAUCAGCAUGGCATT3′ Cyc-B3 antisense (SEQ ID No: 20)5′UGCCAUGUCGAUCUUCACCTT3′ GAPDH sense (SEQ ID No: 21)5′CAUCAUCCCUGCCUCUACUTT-3′ and GAPDH antisense (SEQ ID No: 22)5′AGUAGAGGCAGGGAUGAUG3′

Short oligonucleotides and PNA were also obtained for Eurogentec:

ODN1:  (SEQ ID No: 23) AGCTTAGCTT-Cy5 Cyc-B1a;  (SEQ ID No: 24)TGCCATCGGGCTTGG-Cy5

Fluorescence Titrations

Fluorescence experiments were performed on a PTI spectrofluorimeter at25° C. in a NaCl 154 mM buffer. Intrinsic Trp-fluorescence of VEPEP-9was excited at 290 nm and emission spectrum was recorded between 310 and400 nm, with a spectral band-pass of 2 and 8 nm for excitation andemission, respectively. FITC- or CY5-fluorescence of labelled-peptide orOligonucleotide were excited at 492 nm and emission recorded between 500and 580 nm. For VEPEP-9/peptide interaction, 0.5 μM of FITC-labelledpeptide was titrated by increasing concentrations of VEPEP-9. ForVEPEP-9/oligonucleotide interaction, 200 nM of FITC or CY5-labelledoligodeoxynucleotide (ODN) was titrated by increasing concentrations ofVEPEP-9. All measurements were corrected for the dilution and curvefitting were performed by using Grafit software (Erithacus).

Characterization of Peptide-Based Nanoparticles

Mean particle size distribution was determined with a Coulter N4 Plus(Coulter-Beckman) at 25° C. for 3 min per measurement and zeta potentialwas measured with Zetasizer 4 apparatus (Malvern Ltd,)

Cell Culture and VEPEP-Mediated Cargo Delivery

Adherent HS68 fibroblasts, HeLa, PC3, MCF-7, SCK3-Her2, PBMC cell lines(from American Type Culture Collection (ATCC)) were cultured inDulbecco's Modified Eagle's Medium supplemented with 2 mM glutamine, 1%antibiotics (streptomycin 10,000 μg/ml, penicillin, 10,000 IU/ml) and10% (w/v) foetal calf serum (FCS), at 37° C. in a humidified atmospherecontaining 5% CO₂. Stock solutions of VEPEP-9/peptide particles wereprepared by complexing 1 μM peptide with VEPEP-9 peptides at a molarratio of 1/20 for 30 min at 37° C. Lower concentrations ofVEPEP-9-carrier/peptide (from 500 nM to 1 μM) were obtained by serialdilution of the stock complexes in PBS, in order to preserve the sameVEPEP-9-carrier/peptide ratio. Stock solutions of VEPEP-9/siRNAparticles were prepared by complexing 100 nM siRNA with VEPEP-9 peptidesat a molar ratio of 1/20 for 30 min at 37° C. Lower concentrations ofVEPEP-9/siRNA (from 20 nM to 0.125 nM) were obtained by serial dilutionof the stock complexes in PBS, in order to preserve the sameVEPEP-9/siRNA ratio. 150,000 cells seeded in a 35 mm dish the day priortransfection, were grown to 60% confluence and overlaid with 200 μl ofpreformed complexes, incubated for 3-5 min, then 400 μl of DMEM wereadded. After 30 min. incubation at 37° C., 1 ml of fresh DMEM containing16% foetal calf serum (FCS) was added in order to reach a final FCSconcentration of 10%, without removing the overlay of VEPEP-9/cargocomplexes. Cells were returned to the incubator for 24 hrs. For cdk2derived peptides, cell proliferation was monitored after 24 and 48 hrs.For siRNA targeting Cyclin B1, Cyclin B1 mRNA level was determined 24hrs following transduction, using Quantigen (Panomics Inc.). Datareported are an average of 3 or 4 distinct experiments.

Cytotoxicity

Toxicity of VEPEP-9/peptide or VEPEP-9/ODN complexes was investigated onHela and HS-68 cell lines. 30,000 cells seeded in 24-well plated the dayprior transfection, were incubated with increasing concentrations ofpeptide or ODN complexed with VEPEP-9 at a 20/1 molar ratio ranging from1 to 5 μM (500 μM VEPEP-9), for 30 min prior to addition of medium toreach a final 10% concentration of FCS. Cytotoxic response was measured12 hr or 24 hr later by monitoring the housekeeping gene cyclophilinnRNA level (Quantigen, Panomic Inc.) and by colorimetric MTT assay(Sigma, Germany), respectively. For MTT assay, cell culture medium wasremoved and replaced with PBS containing 2.5 mg/ml of MTT for 4 hr.Results correspond to the average of 3 separate experiments.

Mouse Tumour Models

Athymic female nude mice (6-8 weeks of age) were subcutaneouslyinoculated into the flank with 1×10⁶ PC3, A549 or SCK-3-HEK2 cells in100 μl PBS.

For Peptide treatments: Two to three weeks after tumour implant, whentumour size reached about 100 mm³ animals were treated by intratumoralor intravenous injection, every 3 days, with a solution of 0.1 ml ofeither free Cdk2 derived peptide (200 μg), control scramble peptide C2S(VTLMEAKKQVLT (SEQ ID No: 53)) or C2 (KKQVLAMEHLVT (SEQ ID No: 54))peptides (10, 50, 100 μg) complexed with NANOPEP-9 at a 1/20 molarratio.

For small molecule treatments: Two to three weeks after tumour implant,when tumour size reached about 100 mm³, animals were treated byintratumoral or intravenous injection, every 3 days, with a solution of0.1 ml of either free daunomycine (1 mg), or daunomycine (0.1, 0.2 mg)complexed with NANOPEP-9 at a 1/30 molar ratio or formulationscontaining 15% PEG-NANOPEP-9 at the surface.

For siRNA treatment: Two to three weeks after tumour implant, whentumour size reached about 100 mm³, animals were treated by intratumoralor intravenous injection, every 3 days, with a solution of 0.1 ml ofeither free Cyc-B1 siRNA (50 or 100 μg), control siRNA Cyc-B3 or Cyc-B1siRNA (1, 5, 10 μg) complexed with NANOPEP-9 at a 1/20 molar ratio.

For PNA treatment: Two to three weeks after tumour implant, when tumoursize reached about 100 mm³, animals were treated by intratumoral orintravenous injection, every 3 days, with a solution of 0.1 ml of eitherfree Cyc-B1PNA (50 or 100 μg), or Cyc-B1PNA (1, 5, 10 μg) complexed withNANOPEP-9 or NANOPEP-9/PEG-NANOPEP-9 at a 1/20 molar ratio. Formulationscontaining 15% PEG-NANOPEP-9 were prepared in a stepwise fashion byfirst forming a precomplex of NANOPEP-9/PNA at molar ratio of 1/20,followed by addition of PEG-NANOPEP-9 so as to increase the ratio ofPNA/carrier to 1/25.

Tumour diameter was measured in two directions at regular intervalsusing a digital calliper and tumour volume was calculated aslength×width×height×0.52. Curves show the mean value of tumour size in acohort of six animals and neither animal death nor any sign of toxicitywere observed. Experiments were performed according to nationalregulations and approved by the local animal experimentation ethicalcommittee. The statistical significance of the results was calculated byStudent's t test and p<0.05 considered to be statistically significant.

In Vivo Imaging of Peptide/siRNA Biodistribution

In vivo fluorescence imaging was performed as previously described byCrombez et al, 2009, Nucleic acid res. [10]. Mice were injectedintravenously with 100 μg (200 μl) of Alexa700 fluorescently labelledpeptide (C4 or tetra-peptide: GWASC, SEQ ID No: 52)) or siRNA eithernaked or complexed with VEPEP-9 (n 4 animals per group). Anaesthetizedmice, using 2% Isoflurane, were illuminated by 663 nm light emittingdiodes equipped with interference filters and movies were acquired overthe first 15 minutes and fluorescence images were taken every hour for 5hrs and then after 24 hrs, with a back-thinned CCD cooled camera aspreviously described (Crombez et al, supra). At 24 hr, mice wereeuthanized and different organs were removed for quantification of Alexafluorescence.

Example 2 VEPEP-9 Peptides Applications for Molecules Delivery Example2.1 VEPEP-9 Peptides Form Stable Nanostructures with Cargoes

VEPEP-9 peptide form stable complexes with peptides and ODN. The bindingof cargos to VEPEP-9 was monitored by fluorescence spectroscopy usingthe both intrinsic Trp group of VEPEP-9 (3 to 5 Trp-residues) andextrinsic fluorescently labelled cargoes (using Cy3, Cy5 or FITC). Curvefitting reveal that VEPEP-9 strongly binds the different cargoes withdissociation constant in the nanomolar range (Tables 1 and 2 and FIG.2).

VEPEP-9 peptides form stable particles with different cargoes includingpeptide, siRNA, PNA and small aromatic (FIG. 2). The dissociationconstant for peptide, siRNA, PNA and small hydrophobic molecule rangesbetween 10-100 nM, 5-50 nM, 5-50 nM and 0.02 to 0.2 μM, respectively,depending on the nature of the dyes and of the cargoes.

TABLE 1 VEPEP-9/Cargo complexes characterization. Peptide (C4), siRNA,PNA (15 mer -PNA), and small hydrophobic molecule. Cargoes peptide siRNAPNA SHM Bind- Kd Bind- Kd Bind- Kd Bind- Kd VEPEP-9 ing (nM) ing (nM)ing (nM) ing (μM) VEPEP-9a: yes 10-100 yes 5-50 Yes 5-50 Yes 0.02-0.1VEPEP-9b yes 10-100 yes 5-50 Yes 5-50 Yes 0.02-0.1 VEPEP-9c: yes 10-100yes 5-50 Yes 5-50 Yes 0.02-0.1 VEPEP-9d: yes 10-100 yes >200 Yes >50 Yes0.02-0.1 VEPEP-9e yes 10-100 yes 5-50 Yes 5-50 Yes 0.02-0.1 VEPEP-9f:yes 10-100 yes >200 Yes >50 Yes 0.02-0.1

Binding of small molecule cargoes has been investigated in detaileddepending on the nature of the SHM. Several hydrophobic molecules havebeen used (Daunomycin, Paclitaxel, doxorubicin, porphyrin), as well ascharged molecules (nucleotide, nucleoside and fluorescent dyes).

TABLE 2 VEPEP-9/Cargo complexes characterization. Cargoes FAM-Doxorubicin porphyrin AZT guanosine Bind- Kd Bind- Kd Bind- Kd Bind- KdVEPEP-9 ing (μM) ing (μM) ing (μM) ing (μM) VEPEP-9a: yes 0.02 yes 0.4yes 0.4 yes 0.02 VEPEP-9b yes 0.07 yes 0.5 yes 0.5 yes 0.3 VEPEP-9c: yes0.01 yes 0.08 yes 0.03 yes 0.09 VEPEP-9d: yes 0.09 yes 0.25 yes 0.02 yes0.4 VEPEP-9e yes 0.05 yes 0.20 yes 0.09 yes 1.1 VEPEP-9f: yes 0.01 yes0.11 No — yes 0.8 SHM: small hydrophobic molecules (porphyrin, FAM-G,AZT, doxorubicin)

Example 2.2 VEPEP-9 Peptides Form Stable Nanoparticles with theirDifferent Cargoes

The size of the particles was monitored by dynamic light scattering. Forall the VEPEP-9 peptides, optimal VEPEP-9 peptide/cargo molar ratio isranging between 1/5 to 1/30 (FIG. 3). The size of the particles is ofabout 50 to 200 nanometer in diameter.

Example 3 VEPEP-9 Applications in Cultured Cells Example 3d VEPEP-9Mediated Delivery of Peptide and siRNA in Different Cell Lines

VEPEP-9 peptides have been used for the delivery of different peptidesand siRNA into different cell lines, including primary cell lines, stemcell lines and challenging cell lines. Peptide or siRNA delivery wasmonitored using two approaches: fluorescence spectroscopy and bymonitoring biological responses (anti proliferation, siRNA relatedknockdown).

1—Fluorescent labelled peptide was visualized in the different celllines using fluorescence microscopy or FACS sorting (Table 3). In mostof the cell lines, the uptake of Cy-5 labelled peptides is more than 70%of the cells

2—Dose-response experiments performed on different cultured cellsrevealed that VEPEP-9-mediated delivery of C4 peptides, targetingcdk2/cyclin A complex, block cell proliferation of different cancercells (FIG. 4).

3—Dose-response experiments performed on different cultured cellsrevealed that VEPEP-9-mediated delivery of siRNA (GAPDH) induced arobust downregulation of GAPDH mRNA level (Table 3). In most of the celllines, knockdown (KO) higher than 70% was obtained at the protein level.

Efficiency FACS Efficiency Cell lines origin Cy-5 C4 KO GAPDH Hela Humanepithelial 70% 90% cervical cancer cells STEM-CE Mouse embryonic stem70% 65% cells Jurkat Human T lymphocyte 90% 90% HcpG2 Human hepatocyte70% 70% C2C12 Mouse myoblast 80% 90% MEF Mouse fibroblast 75% 80% HS-68Human fibroblast 90% 80% CEM-SS Human macrophage 60% 70% U20S Humanosteoblast 91% 91% MCF7 Human breast 70% 70% adenocarcinoma MT4 Human Tlymphocyte 75% 70% HER2 Human breast cancer 90% 90% MDA-MB Human breastcancer 70% 70% PBMC Human macrophage 90% 90%

Example 3.2 VEPEP9-Mediated Delivery of Peptide Targeting Cdk2/Cyclin Aor siRNA Targeting Cyclin B1 Induces G2 Arrest and Blocks Cancer CellProliferation

Dose-response experiments performed on cultured cells revealed thatVEPEP-9 mediated delivery of C4 peptide and siRNA (targeting cyclin B1:Cyc-B1) induced a robust biological response associated with specificcell cycle arrest in G2.

For peptide delivery, VEPEP-9a and VEPEP-9f vectors were used. A C4peptide concentration of 200 nM was sufficient to block proliferation ofHela, MCF7, HEK-2 and U2OS cells. IC₅₀ of 45±20 nM and 56±12 nM wereestimated on Hela and MCF7, respectively. For siRNA delivery, VEPEP-9band VEPEP-9e were used. A siRNA concentration of 20 nM was sufficient toblock proliferation of Hela, MCF7, HEK-2 and U2OS cells. IC₅₀ of 3.1±0.2nM, 1.6±0.5 nM and 4.2±1; 2 nM were estimated on Hela, MCF7 and HEK-2respectively. In contrast, for both siRNA and C4 delivery proliferationwas only reduced by 10% for non-transformed HS68 fibroblasts (FIG. 5),in perfect agreement with the impact of the check point G2-M on the cellcycle proliferation and showing the specificity of the peptide forcancer cells.

C4 mediated dissociation of CDK2/cyclin A complex was directlyassociated with accumulation of cells with a 4N content, consistent withdownregulation of Cdk1-Cyclin B1 activity, and was optimally obtainedwith 200 nM peptide and IC₅₀ values estimated to 42±12 nM and 52±15 nMfor HeLa and MCF7 cells, respectively (FIG. 6). In contrast, no effecton cell cycle progression was observed with 500 nM of a scrambled C4peptide, complexed with VEPEP-9 at a 20/1 ratio, or with VEPEP-9a orVEPEP-9f carrier alone (200 μM).

SiRNA-mediated reduction of cyclin B1 protein levels was directlyassociated with accumulation of cells with a 4N content, consistent withdownregulation of Cdk1-Cyclin B1 activity, and was optimally obtainedwith 20 nM siRNA and IC₅₀ values estimated to 2.4±0.8 nM, 1.9±0.9 nM and1.2±0.6 nM for HeLa, MCF7 and HEK-2 respectively (FIG. 7). In contrast,no effect on cyclin B1 levels and cell cycle progression was observedwith 200 nM of an unrelated siRNA (si-GAPDH), or of a mismatch siRNAharbouring two mutations (Cyc-B3) complexed with VEPEP-9 at a 20/1ratio, or with VEPEP-9b and VEPEP-9e carrier alone (100 μM).

Example 3.3 VEPEP-9 Mediated Delivery of Small Peptides in DifferentCell Lines

VEPEP-9a, VEPEP-9c and VEPEP-9f have been used for the delivery of smallpeptides into different cell lines, including primary cell lines, stemcell lines and challenging cell lines. Cargoes uptake was monitoredusing fluorescence spectroscopy and FACS analysis. Fluorescentlylabelled peptides were visualized in the different cell lines usingfluorescence microscopy or FACS sorting (Table 4). In most of the celllines, the uptake of Cy-5 labelled peptide is more than 70% of thecells.

Efficiency Efficiency Efficiency Cell lines origin VEPEP-9a VEPEP-9cVEPEP-9f Hela Human epithelial 70% 80% 60% cervical cancer cells JurkatHuman T lymphocyte 65% 57% 65% SEM Mouse embryonic stem 51% 87% 76%cells HepG2 Human hepatocyte 71% 75% 48% C2C12 Mouse myoblast 59% 90%57% MEF Mouse fibroblast 65% 65% 75% HS-68 Human fibroblast 77% 81% 67%CEM-SS Human macrophage 52% 80% 87% U2OS Human osteoblast 79% 78% 57%MCF7 Human breast 67% 72% 89% adenocarcinoma MT4 Human T lymphocyte 52%47% 56%

Example 3.4 VEPEP9-Mediated Delivery of Peptide and ODN is not Toxic

As shown on FIG. 8, the toxicity of VEPEP-9 particles was investigatedon HeLa, U2OS and STEM ES cells by MTT assay and by monitoring the levelof cyclophilin mRNA measured by Quantigen™ technology (Affymetrix). Notoxicity was detected at levels up to 200 nM, and only a mild toxicitywas observed at the maximum concentration of 1 μM.

Example 3.5 VEPEP-9 Mediated Delivery of PNA Molecule in Different CellLines

VEPEP-9 peptides have been used for the delivery of nucleic acidanalogues (PNA and morpholino) into different cell lines, includingprimary cell lines and challenging cell lines. We demonstrated thatVEPEP-9a, VEPEP-9c and VEPEP-9f form stable complexes with small PNA ormorpholino oligonucleotides of 15 mer and have used them for thedelivery of PNA into different cell lines, including primary cell lines,stem cell lines and challenging cell lines. Uptake was monitored usingfluorescence spectroscopy and following biological response (Cyclin B1knockdown).

Fluorescently labelled PNA was visualized in the different cell linesusing fluorescence microscopy or FACS sorting (Table 5). In most of thecell lines, the uptake of Cy-5 labelled PNA is more than 60% of thecells.

Efficiency Efficiency Efficiency Cell lines origin VEPEP-9a VEPEP-9cVEPEP-9f Hela Human epithelial 67% 82% 78% cervical cancer cells JurkatHuman T lymphocyte 55% 77% 81% SEM Mouse embryonic stem 72% 76% 88%cells HepG2 Human hepatocyte 81% 84% 71% C2C12 Mouse myoblast 65% 89%69% MEF Mouse fibroblast 60% 76% 74% HS-68 Human fibroblast 87% 91% 71%CEM-SS Human macrophage 47% 67% 78% U2OS Human osteoblast 64% 71% 89%MCF7 Human breast 78% 78% 83% adenocarcinoma MT4 Human T lymphocyte 76%54% 67%

We then have applied VEPEP-9a and VEPEP-9f strategy for the delivery ofPNA antisense targeting Cyclin B1 as previously described (Morris et al,2007). Dose-response experiments performed on different cultured cellsrevealed that VEPEP-9-mediated delivery of PNA (Cyclin B1) induced arobust downregulation higher than 70% of Cyclin B1 protein level in Helaand MCF7 cells and no change in Cyclin B1 level was observed with freePNA and scrambled PNA molecule complexed with VEPEP-9 carrier (FIG. 9).

Example 3.6 VEPEP-9 Mediated Delivery of Small Hydrophobic Molecules inDifferent Cell Lines

VEPEP-9 peptides (VEPEP-9a, b, d, f variants) have been used for thedelivery of different small fluorescent hydrophobic and chargedmolecules as well as doxorubicin/porphyrin/taxol on different cell linesincluding primary cell lines and challenging cell lines. VEPEP-9peptides form stable particles with small aromatic molecules includingdoxorubicin or fluorescent dyes (FIG. 10). The dissociation constant forsmall hydrophobic molecules ranges between 0.01 to 2 μM, depending onthe nature of the dyes and of the molecule.

Effect of VEPEP-9 mediated delivery of doxorubicin and porphyrin ortaxol have been investigated on cancer cell viability, the differentSMHs were complexed with VEPEP-9 peptide at a molar ratio of 1/20. Theimpact of carrier peptides to improve cellular uptake of small moleculedrugs was estimated by following inhibition of proliferation of cancercells. Dose-response experiments performed on cultured cells revealedthat VEPEP-9 mediated delivery of doxorubicin, porphyrin and taxolinduced a biological response associated to cell cycle arrest anddecrease in viability of MCF7, SCK-3-HEK2 cancer cells (FIG. 10).

IC₅₀ are reported in Table 6. Comparison of VEPEP-9 mediated drugdelivery with the response obtained with free drug, demonstrated thatDoxo, porphyrin and taxol are between 25 to 50-fold more efficient whencomplexed with VEPEP-9.

TABLE 6 VEPEP-9a VEPEP-9b VEPEP-9d VEPEP-9f Free drug Drug IC50 (μM)IC50 (μM) IC50 (μM) IC50 (μM) IC50 (μM) Doxo 0.2 0.3 0.4 0.6 10 (SKB3)Doxo 0.1 0.2 0.17 0.7 9 (MCF7) Porphyrin 0.8 1.4 0.54 1.2 25 (MCF7)Porphyrin 1.2 0.9 0.87 1.4 17 (SKB3) Taxol 0.8 0.12 0.5 0.8 7 (MCF7)Taxol 0.7 0.65 0.7 0.9 10 (SKB3)

Example 4 NANOPEP-9 Formulations and Applications for In Vivo Delivery

NANOPEP particles contain a “peptide-core” or “core shell” correspondingto the association of either VEPEP-9 peptide or any other peptideforming non covalent complexes with its respective cargo, that issurrounded by additional VEPEP-9 “peripheral” peptides stabilizing theparticle and favouring cell membrane association. The efficiency ofNANOPEP is mainly controlled by the size and the charge of theparticles, which should be ranging between 100-200 nm and ⁺5-⁺20 Volts,respectively. Several combinations can be used for the “core” andperipheral VEPEP-9 can be functionalized or not. The choice of thepeptides in the “core” is dependent on the nature of the cargoes and canbe either VEPEP-9, one of the VEPEP-family peptides (VEPEP-6, VEPEP-3, .. . ), CADY (Crombez et al, 2009a [10]), MPG (Crombez et al, 2009b [1])or PEP-1 (Chariot: Morris et al, 2001 [8]).

The NANOPEP particles are formed in a two step process (FIG. 11): firstthe “core” at molar ratio of 1/5 or 1/10, and then the “peripheral” atmolar ratio of 1/20 up to 1/80. The multilayer organization of theparticle allows their oriented functionalization, which is chosendepending on the nature of the cellular target/tissue and administrationmode.

A three step protocol (FIG. 11) has been established when particlefunctionalization takes place via the nitrilotriacetic acid (NTA) linkedto the VEPEP-9. NTA-group is well known as being able to chelate metaland to strongly interact with histidine tagged protein. Coating of theparticles with NTA-functionalized VEPEP-9 allows the attachment anyprotein harboring a histidine tag to the particle. That strategy offersthe major advantage of having a common 2 layers particles “NANOPEPHIS”that can be associated to any His-tagged protein. The NANOPEPHISstrategy has been used to coat the particles with specific antibodytargeting cell surface antigen (EGF, HER-2 or MUC1) or nanobody selectedby phage display against specific cell line for targeted-delivery ofpeptide. NANOPEPHIS-9 strategy can be universally used to any peptidesand proteins harbouring a Histidine cluster in their sequence.

Example 5 In Vivo Application of NANOPEP-9 Strategy

NANOPEP-9 strategy has been used for in vivo delivery and targeting ofdifferent cargos and different peptide-based nanoparticles. Differentexamples of NANOPEP-9 applications are reported thereafter for peptide(5.1), siRNA (5.2), PNA (5.3) and small molecule (5.4).

Example 5.1 NANOPEP-9 Mediated Short Peptide In Vivo Targeted Deliveryafter Systemic Intravenous or Topical Injections

NANOPEP-9/Peptide Formulations for In Vivo Administration

The therapeutic potential of the NANOPEP-9 technology has been validatedin vivo with peptides targeting CDK2/CYCLIN A/E, an essential proteinkinase required for the control of cell cycle progression in G1 and G2and established therapeutic target in several cancers. The potency ofthis technology has been validated in vivo with peptides targetinginteraction between protein kinase and its cyclin regulators, requiredfor entry and progression through mitosis. Peptide C4 combined withNANOPEP (VEPEP-9a or VEPEP-9f) prevents lung and prostate tumour growthin xenografted mouse models, upon injection every three days ofNANOPEP-9/C4 at 1 mg/kg (FIG. 12). The “core” shell of the particles wasformed using VEVEP-9a or VEPEP-9f peptides at a molar ratio of 20/1 withC4 peptides. VEPEP-9 peptides were solubilised in water and stocksolution of peptide was sonicated for 10 min. in a water bath beforecomplex formation. Then VEPEP-9/peptide complexes were formed by addingC4 peptide into the peptide solution and incubating at 37° C. for 20-30minutes to allow the carrier peptide/peptide complexes to form. Then theparticles were coated with either VEPEP-9a (NANOPEP-9a) peptide orVEPEP-9f (NANOPEP-9f) peptides.

The stability of drug-carrier formulations in vivo and in the bloodcirculation is a major issue for systemic administration oftherapeutics. In order to improve the bioavailability and stability ofthe NANOPEP-9/peptide particles, they were coated with PEG-VEPEP-9,thereby rendering them more suitable for systemic administration. Thesurface layer of NANOPEP-9 particles was functionalized with aPEG-moiety at the N-terminus of VEPEP-9 (PEG-VEPEP-9a), throughactivation of the N-terminal beta alanine amino group.Pegylated-NANOPEP-9a/C4 particles were obtained stepwise by complexingVEPEP-9a molecules with C4 at a molar ratio of 15/1, followed by coatingof particles with a second layer of PEG-VEPEP-9a at ratio 1/10 and thenincubating for 20 minutes at 37° C. for obtaining stable complexes (seeFIG. 11). Particles can be lyophilized for long time storage; in thatcase, 5 to 20% of glucose or manitol are added to the particle solutionbefore lyophilization to stabilize the particles during the process.Before administration, the particles have been diluted in physiologicalconditions, in the presence of 0.9% NaCl and 5 to 20% glucose ormanitol. Following that manufacturing process, more than 95% of the C4peptides are trapped in the nanoparticles, and the particles are stablefor more than 9 months at 4° C., 20° C., −4° C. and −80° C.

NANOPEP-9/C4 Delivery Upon Topical and Systemic Injection

The potential of NANOPEP-9 to deliver C4 peptide in vivo was evaluatedon both human prostate carcinoma cell PC3 and SKB3-HEK2 xenografted mice(FIG. 12). The effect of local intratumoral and systemic intravenousadministration of NANOPEP-9a/C4 or NANOPEP-9f/C2 particles (molar ratio20/1) on the growth of established subcutaneous tumours was evaluated.At day 50, tumor sizes in the control cohort, injected with PBS hadincreased by about 4.0 fold. Upon local intratumoral treatment, everyfour days, reductions of tumor growth by about 70% and 65% were observedusing 100 μg (0.5 mg/kg) of C4/NANOPEP-9a and C4/NANOPEP-9f, for PC3 andSKB3-HEK2, respectively. In both cases, tumour growth was completelyprevented with 200 μg (1 mg/kg) C4/NANOPEP-9a and C4/NANOPEP-9f (FIG.12).

Upon systemic intravenous administration, reductions of tumor growth by45% and 30% were observed using 200 μg (1 mg/kg) of C4/NANOPEP-9a andC′/NANOPEP-9f, respectively. In contrast, when C4 peptide is associatedto functionalized-NANOPEP-9a particles, its potency to inhibit tumourgrowth after systemic intravenous administration is significantlyimproved. 100 μg (0.5 mg/kg) of C4 peptide complexed with PEG-NANOPEP-9fat a 1/20 ratio were injected intravenously every three days into micebearing PC3 or SKB3-HEK2 xenografted tumors and a significant reductionin tumor size of 90% was observed at day 50 (FIG. 12), which is 10 to20-fold more potent than the non functionalized-NANOPEP-9 nanoparticle,suggesting that PEG-increases the biodistribution of peptide in thetumour by maintaining peptide in the plasma and by stabilizing theNANOPEP-9 particle.

In both cases, inhibition of tumour growth was C4 sequence-specific asscrambled peptides C4S or complexed with NANOPEP-9a or NANOPEP-9f andinjected into mice at 2 mg/kg was unable to inhibit tumour growth. Theresults demonstrated that NANOPEP-9 particles are less efficient viasystemic injection, which is probably due to lower stability in theblood of the particle (see below).

Example 5.2 NANOPEP-9 Mediated siRNA In Viva Targeted Delivery afterSystemic Intravenous or Topical Injections

Combining cyclin B1 siRNA with NANOPEP-9 prevents lung, ovarian andprostate tumour growth in xenografted mouse models, upon injection everythree days of NANOPEP-9/siRNA complexes (FIG. 13).

Athymic female nude mice (6-8 weeks of age) were subcutaneouslyinoculated into the flank with 1×10 PC3 (prostate cancer), A549 (lungcancer) or SCK-3-HEK2 (ovarian cancer) cells in 100 μl PBS. Two to threeweeks after tumour implant, when tumour size reached about 100 mm³,animals were treated by intratumoral or intravenous injection, every 3days, with a solution of 0.1 ml of either free Cyc-B1 siRNA (50 or 100μg), control siRNA Cyc-B3 or Cyc-B1 siRNA (5, 10 μg) complexed withNANOPEP-9b or NANOPEP-9e particles. The “core” shell of the particleswas formed using VEVEP-9b or VEPEP-9e peptide at a molar ratio of 20/1with a siRNA targeting cycline B1. siRNA stock solutions are in 50 mMIris, 0.5 mM EDTA buffer or in RNase free water. VEPEP-9 peptides weresolubilised in water and stock solution of peptide was sonicated for 10min in a water bath before complex formation. Then VEPEP-9/siRNAcomplexes were formed by adding siRNA into the peptide solution andincubating at 37° C. for 20-30 minutes to allow the carrierpeptide/siRNA complexes to form. NANOPEP-9 particles contain aVEPEP-9/siRNA “core shell” surrounded by additional VEPEP-9 at a 1/20molar ratio.

Tumour diameter was measured in two directions at regular intervalsusing a digital calliper and tumour volume was calculated aslength×width×height×0.52. Curves show the mean value of tumour size in acohort of six animals and neither animal death nor any sign of toxicitywere observed. Experiments were performed according to nationalregulations and approved by the local animal experimentation ethicalcommittee. The statistical significance of the results was calculated byStudent's t test and p<0.05 considered to be statistically significant.The stock solutions of particles were done in water and stable for atleast three weeks at 4° C. Particles can be lyophilized for long timestorage; in that case, 5 to 20% of glucose is added to the particlesolution before lyophilization to stabilize the particles during theprocess. Before administration the particles were diluted inphysiological conditions, in the presence of 0.9% NaCl and 5 to 20%manitol.

NANOPEP-9 Cyclin B1 siRNA Delivery Upon Topical Injection

The potential of NANOPEP-9b or NANOPEP-9e to deliver cyclin B1 siRNA invivo was evaluated on PC3. A549, or SCK-3-HEK2-xenografted mice (FIG.13). The effect of local intratumoral administration of NANOPEP-9/siRNAparticles (molar ratio 20/1) on the growth of established subcutaneoustumours was evaluated. At day 50, tumor sizes in the control cohort,injected with PBS increased by about 3 to 5 fold. Reductions of tumorgrowth by 80% (PC3 and A549) and by 65% (SCK-3-HEK2), were observedusing 1 μg of cyclin B1 siRNA in NANOPEP-9/siRNA and in all the cases,tumour growth was completely prevented with 5 μg (0.25 mg/kg) of cyclinB1 siRNA in NANOPEP-9/siRNA (FIG. 13). At day 48, it was validated thatthe Cyc-B1 siRNA mediated inhibition of tumour growth was directlyassociated with a decrease in the level of cyclin B1 mRNA. As a control,administration of 100 μg (intratumoral or intravenous) naked siRNA orNANOPEP-9 carrier alone had no significant effect on tumour growth.Moreover, inhibition of tumour growth was siRNA sequence-specific as acyclin B1 siRNA harbouring two mutations (Cyc-B3) complexed withNANOPEP-9e and injected into mice at 0.5 mg/kg was unable to inhibittumour growth.

NANOPEP-9 Cyclin B1 siRNA Delivery Upon Systemic Injection

NANOPEP-9b and NANOPEP-9e particles were used for systemic intravenousadministration. Five micrograms (0.25 mg/kg) and 10 μg (0.5 mg/kg) ofCyc B1 siRNA in NANOPEP-9b and NANOPEP-9e particles were injectedintravenously every three days into mice bearing xenografted tumors. Asignificant reduction in PC3 tumor size was observed at day 50, with 65%and 90% inhibition with 5 μg and 10 μg of siRNA, respectively (FIG. 13).A significant reduction in HT29 tumor size was observed at day 50, with35% and 70% inhibition with 5 μg and 10 μg of siRNA, respectively(Figure xx). These results together with the lack of anti-tumoralactivity of the NANOPEP-9/mismatch siRNA (10 μg) or of NANOPEP-9 carrieralone, underscores the robustness and specificity of the biologicalresponse associated with systemic delivery of cyclin B1 siRNA

Example 5.3 NANOPEP-9 Mediated Anti Cyclin B1 PNA Antisens Delivery UponSystemic Injection

NANOPEP-9a and NANOPEP-9c were used for the delivery of antisense PNAtargeting cyclin B1 antisense in vivo. NANOPEP-9a/PNA, NANOPEP-9c/PNAand NANOPEP-9a/PNA particles coated with PEG-VEPEP-9a were evaluateddirectly on the potency to inhibit tumour growth. The particles wereused for systemic intravenous administration into SKB3-HEK2 xenograftedtumor mouse model. The surface layer of NANOPEP-9a particles wasfunctionalized with a PEG-moiety at the N-terminus of VEPEP-9a(PEG-VEPEP-9a), through activation of the N-terminal beta-alanine aminogroup. Pegylated-NANOPEP-9a/PNA particles were obtained stepwise bycomplexing VEPEP-9a molecules with PNA at a molar ratio of 10/1,followed by coating of particles with a second layer of PEG-VEPEP-9a atratio 1/10. 10 μg of PNA complexed with NANOPEP-9a, NANOPEP-9e andPEG-NANOPEP-9a at a 1/30 ratio were injected intravenously every threedays into mice bearing SKB3-HEK2 xenografted tumor. As reported in FIG.14, at day 50, reductions of tumor growth by 35 and 42% were obtainedwith 10 μg of PNA complexed with NANOPEP-9a and NANOPEP-9e,respectively. A significant reduction in tumor size of 78% was observedwith 10 μg of PNA complexed with PEG-NANOPEP-9a, at day 50 (FIG. 14).Inhibition of tumour growth was PNA cyclin B1 sequence-specific as 50 μgscrambled PNA complexed with NANOPEP-9a and injected into mice wasunable to inhibit tumour growth. These results show that VEPEP-9a andVEPEP-9e constitute great carriers for in vivo delivery of PNA and thatPEG-increases the biodistribution of PNA in the tumour by improving thestability of the NANOPEP-9 particle.

Example 5.4 NANOPEP-9 Mediated Doxomycin In Vivo Delivery Upon SystemicInjection

NANOPEP-9 peptides (VEPEP-9a, b, d, f variants) have been used for thedelivery of doxorubicin in vivo. The potential of NANOPEP-9 to deliverdoxorubicin in vivo was evaluated on SKB3-HEK2 xenografted mice.Doxorubicin was complexed with VEPEP-9 peptide at a molar ratio of 1/20with NANOPEP-9a, NANOPEP-9f and NANOPEP-9a-PEG. The treatment wasstarted 10 days after tumor inoculation and with 2 mg/kg and 10 mg/Kgdoses of drug and injected every 4 days by systemic Intravenousadministration and mice were monitored for survival (FIG. 15). Theresults demonstrate a survival rate of 10 days in the absence of anydrug, of 16 days with free Doxo (20 mg/Kg), of 32 and 45 days with 10mg/kg complexed with NANOPEP-9a or NANOPEP-f, respectively. Whenparticles are coated with PEG-NANOPEP-9a, more than 45% of the mice werestill surviving after 50 days, suggesting that PEGylation dramaticallyimproves the bioavailability of the particles.

Example 5.5 NANOPEP-9 Mediated In Vivo Delivery of Cargo Via DifferentAdministration Routes

NANOPEP-9 based particles have been evaluated using differentadministration routes including systemic intravenous, intrarectal,intranasal and transdermal administrations.

A fluorescently labelled peptide or siRNA with Alexa 700 was complexedinto NANOPEP-9a or NANOPEP-9b particles. Biodistribution of thefluorescently labelled peptide or siRNA was evaluated in vivo on Balb6Mouse, 5 hr after a single administration of 10 μg peptide or siRNA inNANOPEP-9 particles. Intravenous and intrarectal administrations of theNANOPEP-9/peptide or NANOPEP-9/siRNA complex allowed the delivery of thecargoes in most of the analyzed tissues, with a significant delivery inthe lung and muscle (FIG. 16). Intranasal and intratrachealadministration allowed the delivery of peptide and siRNA, mainly in thebrain, lung, liver, pancreas and kidney. Finally, transdermaladministration is limited to the delivery of the peptide and siRNA intoand through the skin and muscles, and partially in the liver but not inthe other tissues (FIG. 16).

REFERENCES

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The invention claimed is:
 1. A cell-penetrating peptide characterized inthat it comprises an amino acid sequence:X₁X₂X₃WWX₄X₅WAX₆X₃X₇X₈X₉X₁₀X₁₁X₁₂WX₁₃R (SEQ ID No: 10), wherein X₁ isbeta-A or S, X₂ is L or none, X₃ is R or none, X₄ is L, R or G, X₅ is R,W or S, X₆ is S, P or T, X₇ is W or P, X₈ is F, A or R, X₉ is S, L, P orR, X₁₀ is R or S, X₁₁ is W or none, X₁₂ is A, R or none and X₁₃ is W orF, and wherein if X₃ is none, then X₂, X₁₁ and X₁₂ are none as well. 2.The cell-penetrating peptide of claim 1, characterized in that itcomprises an amino acid sequence X₁X₂RWWLRWAX₆RWX₈X₉X₁₀WX₁₂WX₁₃R (SEQ IDNo: 11), wherein X₁ is beta-A or S, X₂ is L or none, X₆ is S or P, X₈ isF or A, X₉ is S, L or P, X₁₀ is R or S, X₁₂ is A or R, and X₁₃ is W orF.
 3. The cell-penetrating peptide of claim 2, wherein the amino acidsequence is selected from the group consisting of: (SEQ ID No: 1)X₁LRWWLRWASRWFSRWAWWR, (SEQ ID No: 2) X₁LRWWLRWASRWASRWAWFR,(SEQ ID No: 3) X₁RWWLRWASRWALSWRWWR, (SEQ ID No: 4)X₁RWWLRWASRWFLSWRWWR, (SEQ ID No: 5) X₁RWWLRWAPRWFPSWRWWR, and(SEQ ID No: 6) X₁RWWLRWASRWAPSWRWWR,

wherein X₁ is beta-A or S.
 4. The cell-penetrating peptide of claim 1,characterized in that it comprises an amino acid sequenceX₁WWX₄X₅WAX₆X₇X₈RX₁₀WWR (SEQ ID No: 12), wherein X₁ is beta-A or S, X₄is R or G, X₅ is W or S, X₆ is S, T or P, X₇ is W or P, X₈ is A or R,and X₁₀ is S or R.
 5. The cell-penetrating peptide of claim 4, whereinthe amino acid sequence is selected from the group consisting of:(SEQ ID No: 7) X₁WWRWWASWARSWWR, (SEQ ID No: 8) X₁WWGSWATPRRRWWR, and(SEQ ID No: 9) X₁WWRWWAPWARSWWR,

wherein X₁ is beta-A or S.
 6. The cell-penetrating peptide of claim 1,further comprising, covalently linked to the N-terminal end of the aminoacid sequence, one or several chemical entities selected from the groupconsisting of an acetyl, a fatty acid, a cholesterol, a poly-ethyleneglycol, a nuclear localization signal, a nuclear export signal, anantibody, a polysaccharide and a targeting molecule.
 7. Thecell-penetrating peptide of claim 1, further comprising, covalentlylinked to the C-terminal end of said amino acid sequence, one or severalgroups selected from the group consisting of a cysteamide, a cysteine, athiol, an amide, an optionally substituted nitrilotriacetic acid, acarboxyl, a linear or branched optionally substituted C₁-C₆ alkyl, aprimary or secondary amine, a lipid, a phospholipid, a fatty acid, acholesterol, a poly-ethylene glycol, a nuclear localization signal, anuclear export signal, an antibody, a polysaccharide and a targetingmolecule.
 8. A complex comprising a cell-penetrating peptide accordingto claim 1 and a cargo selected amongst peptides, proteins, peptideanalogs, oligonucleotides, PNAs and small hydrophobic molecules.
 9. Thecomplex of claim 8, wherein said cargo is a molecule of at most 1.5 kDa.10. The complex of claim 8, wherein said cargo is an anticancer or ananti-viral drug.
 11. The complex of claim 8, wherein said cargo isselected from the group consisting of siRNA, a mix of siRNAs selected tosilence a target mRNA, miRNA, a mix of miRNAs, oligodeoxynucleotides,amino acids, di- or tri-peptides, daunomycin, Paclitaxel, doxorubicin,AZT, porphyrin, fluorescently labelled nucleosides or nucleotides,hydrophobic maghemite and fluorescent dyes.
 12. The complex of claim 8,wherein the size of the complex is between 50 and 300 nm.
 13. Ananoparticle comprising a complex according to claim 8, coated by alayer of peripheral cell-penetrating peptides, wherein said peripheralcell-penetrating peptides have a peptide sequence different from SEQ IDNo: 10, SEQ ID No: 11 and SEQ ID No:
 12. 14. A nanoparticle comprising acore which comprises a cargo complexed to a first entity selected fromthe group consisting of cell-penetrating peptides, liposomes,polycationic structures and carbon nanoparticles, wherein said core iscoated by peripheral cell-penetrating peptides, and wherein theperipheral cell-penetrating peptides have the peptide sequence of acell-penetrating peptide according to claim
 1. 15. The nanoparticle ofclaim 14, wherein said first entity is a cell-penetrating peptideselected from the group consisting of VEPEP-6a (SEQ ID No: 33), VEPEP-6b(SEQ ID No: 34), VEPEP-6c (SEQ ID No: 35), VEPEP-6d (SEQ ID No: 36),VEPEP-6e (SEQ ID No: 37), VEPEP-6f (SEQ ID No: 38), ST-VEPEP-6a (SEQ IDNo: 41), ST-VEPEP-6aa (SEQ ID No: 42), ST-VEPEP-6ab (SEQ ID No: 43),ST-VEPEP-6ad (SEQ ID No: 44), ST-VEPEP-6b (SEQ ID No: 45), ST-VEPEP-6ba(SEQ ID No: 46), ST-VEPEP-6bb (SEQ ID No: 47), ST-VEPEP-6bd (SEQ ID No:48), ST-VEPEP-6c (SEQ ID No: 49), VEPEP-3a (SEQ ID No: 25), VEPEP-3b(SEQ ID No: 26), VEPEP-3c (SEQ ID No: 27), VEPEP-3d (SEQ ID No: 28),VEPEP-3e (SEQ ID No: 29), VEPEP-3f (SEQ ID No: 30), VEPEP-3g (SEQ ID No:31), VEPEP-3h (SEQ ID No: 32), VEPEP-3bstapl (SEQ ID No: 39),VEPEP-3estapl (SEQ ID No: 40), CADY, MPG, PEP-1, PPTG1, and polyArginine.
 16. The nanoparticle of claim 14, wherein the size of thenanoparticle is between 20 and 300 nm.
 17. The nanoparticle of claim 14,wherein the peripheral cell-penetrating peptides comprise apoly-ethylene glycol group covalently linked to their N-terminus, and/ora cysteamide group covalently linked to their C-terminus.
 18. Thenanoparticle of claim 14, wherein at least some of the peripheralcell-penetrating peptides are bound to a targeting molecule.
 19. Thenanoparticle of claim 14, for use as a medicament.
 20. The nanoparticleof claim 14, for use as a marker or an imaging agent.
 21. A therapeutic,cosmetic or diagnostic composition comprising a nanoparticle accordingto claim
 14. 22. The composition of claim 21, which is formulated forintravenous, intratumoral, topical, intrarectal, intranasal,transdermal, or intradermal administration, or for administration via amouth spray, or for administration as a subcutaneous implant for slowrelease of a drug.
 23. A method for delivering a molecule into a cell invitro, comprising a step of putting said cell into contact with ananoparticle according to claim 14, wherein the cargo of thenanoparticle is said molecule.